Professor CErsted on Water- Spouts. 67 



partly hailstones. We can thus easily imagine that the frozen 

 particles, during all these movements, are sometimes out of 

 contact with warmer and moist air, and also that they are 

 again equally often brought back to situations where they meet 

 them, so that alternately they become so much cooled that 

 the water by which they are coated becomes ice, or they meet 

 moist air in which they acquire a new covering of water. 

 Hence large hailstones may be formed, composed of various 

 layers, the one including the other. 



All this corresponds in the most remarkable manner with 

 the facts observed. Great storms of hail and violent showers 

 of rain almost invariably accompany water-spouts. It may, 

 perhaps, not be too bold to suppose, that the great falls of 

 hail, which so frequently devastate long but narrow tracts of 

 fruitful land, are produced by great air-vortices in the higher 

 regions of the atmosphere, or, if I may be allowed so to ex- 

 press myself, by water-spouts which extend beyond the lower 

 strata of clouds. So far as I can judge, no circumstance oc- 

 ciu-s during great showers of hail, which does not harmonize 

 with this idea. Electricity, which accompanies most hail- 

 storms as well as water-spouts, may perhaps contribute by 

 causing a greater variety of movements than those which arise 

 from vortices, and thus assisting the formation of hail, so 

 that Volta's supposition, that electricity co-operates in pro- 

 ducing hail, here finds an application ; but we should not 

 wish to see oiu-selves forced to assmne this co-operation, in 

 case the presence of electricity should not shew itself so dis- 

 tinctly in all these formations of hail. 



In the axis of water-spouts, and near it, there must also, 

 without doubt, be a portion of watery vapour condensed. 

 From this source, probably, is derived the rain which falls in 

 large drops on ships that encounter water-spouts, and which 

 has been found to consist of fresh water. The water-spout 

 mentioned above, whose effects were so carefully noticed in 

 North America, must also have contained water, as all objects 

 it met with were sprinlcled with mould on the west, that is 

 the side from which it came. 



When moisture is rapidly condensed, electricity is produced, 

 and we have an opportunity of observing this sufficiently well 



